A method for preparing a water-based epoxy-cement-fiber reinforced cold patching material for emergency repair of asphalt pavements in low-temperature, foggy mountainous areas.

Abstract

This invention provides a method for preparing a water-based epoxy-cement-fiber reinforced cold patch for emergency repair of asphalt pavements in low-temperature, foggy mountainous areas. To overcome the technical shortcomings of existing cold patches under low-temperature, foggy mountainous conditions, such as insufficient environmental friendliness, difficulty in balancing workability and early strength, poor low-temperature crack resistance, and inadequate water stability and long-term durability, this application proposes adding appropriate amounts of cement and fiber to the water-based epoxy emulsified asphalt cold patch system to construct a cement-fiber synergistic reinforcement system. This improves the overall toughness and structural stability of the cold patch, significantly enhancing its low-temperature crack resistance, interfacial adhesion, and road durability.

Description

Technical Field

[0001] This invention belongs to the technical field of emergency repair materials for asphalt pavement, specifically relating to a water-based epoxy-cement-fiber reinforced cold patch material suitable for low-temperature, foggy mountain road sections. Especially for the harsh working conditions of low temperature freezing and frequent fog in mountainous areas, by introducing a cement and fiber synergistic reinforcement system into the water-based epoxy emulsified asphalt cold patch material, the low-temperature toughness and structural stability of the material are improved, significantly enhancing its low-temperature crack resistance, interfacial adhesion performance and long-term service durability, thus meeting the technical requirements for emergency maintenance of asphalt pavement in mountainous areas. Background Technology

[0002] With the rapid increase in traffic volume, the intensified impact of heavy-duty vehicles, and the extended service life of road surfaces, asphalt pavements in mountainous areas are highly susceptible to defects such as cracks, ruts, and potholes under harsh conditions such as low temperatures, icing, and frequent fog, seriously affecting road safety and service life. Therefore, developing high-performance cold-mix repair materials suitable for the special environment of mountainous areas to improve emergency maintenance efficiency and repair quality has become a key research focus in the field of road maintenance.

[0003] Existing cold-mix asphalt repair materials are mainly classified into three categories based on the type of binder: solvent-based, emulsified asphalt-based, and reactive. Solvent-based cold-mix asphalt, while having lower requirements for temperature and weather conditions during construction, suffers from issues such as high volatility and poor environmental friendliness. Emulsified asphalt cold-mix asphalt, using emulsified or modified emulsified asphalt as the binder, is environmentally friendly and storage-stable; however, it is difficult to completely remove moisture in the early stages of curing, resulting in lower early strength and insufficient low-temperature crack resistance, rutting resistance, and fatigue resistance, making it unsuitable for service under the combined effects of low temperatures, humidity, and heavy loads in mountainous areas. Reactive cold-mix asphalt, while exhibiting high curing strength and excellent fatigue resistance, has complex construction processes, higher costs, and a significantly reduced reaction rate and prolonged curing period at low temperatures, limiting its application in emergency maintenance scenarios in low-temperature, humid, and foggy mountainous areas. The main disadvantages of existing cold-mix asphalt repair materials are as follows: 1. Solvent-based cold patching materials have the problem of easy volatile organic solvents, which not only endangers the health of construction workers, but also does not meet the current strict environmental protection requirements, significantly limiting their application scenarios. In addition, in the low temperature and humid fog environment of mountainous areas, the solvent evaporation rate is further reduced, resulting in slow early strength formation and poor repair effect.

[0004] 2. Conventional water-based epoxy emulsified asphalt cold patching material has a contradiction between workability and initial strength: In order to adapt to the construction needs in low temperature and humid environment, the material needs to maintain a low viscosity to ensure workability, but this will directly cause the early strength development to be slow, prolong the time to open to traffic, and fail to meet the core requirements of emergency repair in mountainous road sections.

[0005] 3. Conventional water-based epoxy emulsified asphalt cold patch material has a contradiction between strength forming rate and water stability and durability: water in the water-based system is difficult to drain quickly. Under the working conditions of low temperature freezing and frequent damp fog in mountainous areas, water is easy to remain inside the mixture or freeze-thaw damage, which leads to the obstruction of later strength growth, failure of the repair interface bonding, and problems such as early loosening, low temperature cracking, and pothole recurrence. It has insufficient long-term service durability and high maintenance costs.

[0006] To overcome the shortcomings of existing emulsified asphalt cold mix materials, such as insufficient forming strength, poor toughness, and weak crack resistance in low-temperature, humid, and mountainous conditions, this invention proposes a water-based epoxy emulsified asphalt cold patch material technology that synergistically reinforces cement and fibers. By introducing the cement hydration reaction, the early load-bearing capacity and deformation resistance of the mixture are improved. Simultaneously, the reinforcing and bridging effects of fibers are utilized to improve the low-temperature toughness and crack resistance of the mixture, achieving an optimized balance between the forming strength, workability, and long-term durability of the cold patch material.

[0007] This invention, through reasonable mix design and optimization of composite reinforcement system, enables water-based epoxy emulsified asphalt cold patch material to maintain excellent dynamic and road performance under harsh conditions such as low temperature, humidity, and icing. It can effectively improve the construction efficiency and repair quality of emergency maintenance of asphalt pavement in mountainous areas, and has good engineering application prospects and promotion value. Summary of the Invention

[0008] The purpose of this invention is to address the technical shortcomings of existing cold patch materials, such as poor environmental performance, imbalance between workability and initial strength, poor low-temperature crack resistance, and insufficient water stability and long-term durability, in response to the harsh working conditions of low temperature freezing and frequent fog in mountainous areas. The invention provides a high-performance cold patch material that combines excellent workability, rapid early strength, good low-temperature crack resistance, and long-term durability to meet the technical needs of emergency maintenance of asphalt pavements in mountainous areas.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a water-based epoxy-cement-fiber reinforced cold patching material for emergency repair of asphalt pavements in low-temperature, foggy mountainous areas includes the following steps: (1) Preparation of emulsifier: Step 1: Determine the molecular weight of polyethylene glycol (PEG) to be 4000.

[0010] Step 2: Prepare 200g of a mixed solution of E44 and PEG in a mass ratio of 1:1, place it in a 60℃ constant temperature water bath, and adjust the mechanical stirrer speed to 300r / min. Slowly add 10g of 5% K2S2O8 solution. After titration for 30min, transfer it to a 160℃ oil bath for reaction for 6h.

[0011] (2) Preparation of waterborne epoxy resin and determination of curing agent Step 1: Place the emulsifier in a three-necked flask. Calculate the amount of E44 needed according to different mass ratios of emulsifier to E44 (10%, 15%, 20%, 25%, 30%), and add it to the three-necked flask containing the emulsifier. Maintain the water bath temperature at 60℃ and stir at a mechanical speed of 2000 r / min for approximately 0.5 h. Add an appropriate amount of deionized water to prepare an aqueous epoxy resin emulsion with a solid content of 50 wt%.

[0012] Step 2: Select polyamide, fatty amine, epoxy curing agent and self-made waterborne epoxy resin emulsion respectively for compatibility curing test. By comparing the film-forming effect, bonding performance and storage stability of different curing systems, the waterborne curing agent is finally selected.

[0013] (3) Preparation of waterborne epoxy resin emulsified asphalt: After mixing waterborne curing agent modified polyamide with emulsified asphalt, mechanical stirring is performed to obtain a mixture; then waterborne epoxy resin emulsion is added and mechanically stirred at a speed of 400 r / min for 3 to 4 min to obtain waterborne epoxy resin emulsified asphalt.

[0014] (4) Select mineral powder with a relative density of 2.790, and add it in an amount of 2% to 6% of the total mass of cold patching material.

[0015] (5) Based on the total mass of the cold patch material, the fiber used is chopped polyester fiber with a fiber content of 0.2%. The cement is ordinary silicate P.I42.5 with a cement content of 2%. The optimal amount of water-based epoxy resin emulsified asphalt binder is 8.975% of the total mass of the cold patch material.

[0016] (6) Molding, mixing and curing.

[0017] Step 1: Weigh out water at 1.0% of the aggregate mass, then put the aggregate and the added water into a mixing pot and stir for 60 seconds to wet the surface of the aggregate. Step 2: Pour in the appropriate proportion of water-based epoxy resin emulsified asphalt and stir for 60 seconds; Step 3: Add the weighed cement, fiber and mineral powder and mix for 60 seconds.

[0018] Step 4: Concrete the mold on both sides 50 times at room temperature, then cure it in a 60℃ oven for 3 hours. Step 5: After compacting 25 times again, demold and continue curing for 48 hours.

[0019] The core innovation of this application lies in the adaptation design of a cement-chopped polyester fiber synergistic reinforcement system and a customized water-based epoxy emulsified asphalt binder, which solves the technical pain points of slow moisture drainage, low early strength, and poor low-temperature crack resistance of cold-mixed materials under low-temperature, humid, and foggy mountain conditions. The specific improvements are as follows: 1. Synergistic Reinforcement System Design: A composite reinforcement system is constructed using chopped polyester fiber and cement. The chopped polyester fiber content is 0.2% of the total mass of the cold patch material, and the cement content is 2% of the total mass of the cold patch material. The cement replaces part of the mineral powder by an equal mass. Through the synergistic effect of fiber bridging and reinforcement and cement hydration and hardening, the mixture can accelerate the consumption of internal moisture, improve early strength and structural stability, and significantly improve the low-temperature toughness and crack resistance of the material, making it suitable for low-temperature freezing and humid conditions in mountainous areas.

[0020] 2. Preparation of customized waterborne epoxy emulsified asphalt binder: A special epoxy emulsifier is synthesized using epoxy resin (E44) and polyethylene glycol 4000 as raw materials (the amount of emulsifier accounts for 25% of the mass of E44). The emulsifier is then compounded with E44 and water to prepare a waterborne epoxy resin emulsion. BC-1 slow-cracking cationic emulsified asphalt is selected and compounded with the waterborne epoxy resin emulsion and a waterborne curing agent (selected from modified polyetheramine, modified fatty amine, and modified polyamide) to prepare a waterborne epoxy resin emulsified asphalt binder. The optimal dosage is 8.975% of the total mass of the cold patch material.

[0021] 3. Selection and performance matching of key components: The cement is selected from one of the following: composite silicate cement, ordinary silicate cement, and sulfoaluminate cement, with a strength grade of not less than 32.5 to ensure rapid hydration and hardening in low-temperature environments; the short-cut polyester fiber is made by precise cutting of fibers synthesized from organic dicarboxylic acids and diols, with its length and diameter matching the aggregate gradation, which can effectively inhibit the initiation and propagation of low-temperature cracks; the aggregate is selected as clean, dry, hard, rough-surfaced, and angular cubic particles, free of impurities, to ensure interfacial adhesion performance with the binder.

[0022] 4. Low-Temperature Adaptable Mixing Process: A three-stage mixing process is adopted, specifically: First, aggregates and externally added water are placed in a mixing pot and stirred for 60 seconds to fully wet the aggregate surface; then, a pre-proportioned water-based epoxy resin emulsified asphalt is poured in and stirred for 60 seconds to achieve uniform coating; finally, weighed cement, chopped polyester fibers, and mineral powder are added, and mixing continues for 60 seconds until the mixture is uniform and free of lumps. This process avoids the problems of binder demulsification and insufficient aggregate coating under low-temperature conditions, ensuring workability and molding quality.

[0023] 5. Core performance parameters of the mixture: Through the above-mentioned component and process optimization, the dynamic modulus of the final cold patch material remains high in the test loading frequency range under the low temperature condition of -10℃; the material has excellent deformation resistance and interfacial bonding performance under low temperature conditions, which can meet the needs of emergency repair of asphalt pavement in low temperature, humid and foggy mountainous areas.

[0024] The advantages of this invention are: (1) The cold patching material of this application has a high dynamic modulus and low temperature sensitivity under low temperature conditions. The test results show that the dynamic modulus of the material remains at a high level at different loading frequencies when the temperature is -10℃, and the stiffness is sufficient. It can effectively resist the load and deformation under the negative temperature environment in winter and avoid the early damage caused by the insufficient low temperature strength of conventional cold patching materials. At the same time, the modulus changes steadily with temperature and frequency in the low temperature range, and the mechanical response is stable. It can effectively alleviate the temperature stress caused by the large temperature difference between day and night in mountainous areas and inhibit the initiation and propagation of thermal shrinkage cracks.

[0025] (2) Through the synergistic effect of the three-dimensional network crack-resistant effect of short-cut polyester fibers and the hardening effect of cement hydration, the low-temperature toughness and crack resistance of the material are significantly improved, solving the problem of conventional cold patch material being prone to brittle cracking at low temperatures and effectively extending the service life of the repaired road surface.

[0026] (3) The material has both flexibility and structural stability. Its dynamic modulus is higher than that of conventional waterborne epoxy emulsified asphalt cold patch material. It can meet the load-bearing requirements under different traffic conditions and adapt to the use needs of complex traffic scenarios in mountainous areas.

[0027] (4) This application achieves a balance between workability and early strength by combining water-based epoxy resin and emulsified asphalt and using a suitable mixing process. This ensures workability in low-temperature and humid environments and improves the overall performance of the material through synergistic enhancement effect. It can better meet the core requirements of "rapid construction and long-term durability" for emergency maintenance of asphalt pavement in low-temperature, humid and foggy mountainous areas.

[0028] (5) Excellent adaptability to damp and foggy environments. Through the cross-linking and curing of water-based epoxy resin, the hydration of cement, and the bridging effect of fibers, a dense waterproof network is formed. Even under extreme damp and foggy conditions where the aggregate surface is wet (relative humidity ≥90% pre-wetting), the splitting strength of the prepared cold patch can still reach more than 85% of that under dry conditions, which is much higher than that of ordinary emulsified asphalt cold patch, effectively solving the problem of adhesion failure caused by water film during road repair in damp and foggy mountainous areas. Detailed Implementation

[0029] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are provided below for detailed description. Unless otherwise specified, the methods of the present invention are conventional methods in the art. Example 1

[0030] A method for preparing a low-temperature resistant nano-reinforced epoxy recycled asphalt emergency maintenance material includes the following steps: (1) Preparation of emulsifier: Step 1: Determine the molecular weight of PEG to be 4000.

[0031] Step 2: Prepare 200g of a mixed solution of E44 and PEG in a mass ratio of 1:1, place it in a 60℃ constant temperature water bath, and adjust the mechanical stirrer speed to 300r / min. Slowly add 10g of 5% K2S2O8 solution to the three-necked flask. After titration for 30min, transfer the three-necked flask to a 160℃ oil bath for reaction for 6h.

[0032] (2) Preparation of waterborne epoxy resin and determination of curing agent Step 1: Place 100g of emulsifier into a three-necked flask. The amount of emulsifier added should be 25% of the mass of E44 epoxy resin. Calculate and weigh 400g of E44 and add it to the three-necked flask containing the emulsifier. Heat the mixture in a water bath at 60℃ and stir at a mechanical speed of 2000 rpm for approximately 0.5 hours. Add 500g of deionized water to prepare an aqueous epoxy resin emulsion with a solid content of 50wt%.

[0033] Step 2: Select type 650 modified polyamide curing agent (CAS: 63428-84-2) as the matching water-based curing agent.

[0034] (3) Preparation of waterborne epoxy resin emulsified asphalt composite material: First, weigh 250g of 650 type modified polyamide and 1000g of BC-1 type emulsified asphalt, mix the two and mechanically stir to prepare a mixed solution, then add 75g of waterborne epoxy resin emulsion according to the ratio, and mechanically stir at 400 r / min for 3~4 min to obtain waterborne epoxy resin emulsified asphalt.

[0035] (4) Select mineral powder with a relative density of 2.790, and add it at 4% of the total mass of cold-mixed material. Specific parameters are shown in Table 1.

[0036] Table 1 Technical Specifications of Mineral Powder

[0037] (5) Based on the total mass of the cold patch material, the fiber used is chopped polyester fiber (equivalent diameter 20μm±4μm, length 6mm, tensile strength ≥450 MPa, melting point ≥240 ℃), with a fiber content of 0.2%. The cement is ordinary silicate P.I42.5, with a cement content of 2%. The optimal amount of waterborne epoxy resin emulsified asphalt binder is 8.975% of the total mass of the cold patch material. The synthetic gradation of AC-13 graded aggregate is shown in Table 2: Table 2. Synthetic Gradation of AC-13

[0038] (6) Molding, mixing and curing.

[0039] Step 1: Put 8475g of aggregate and 84.75g of externally added water into a mixing pot and stir for 60 seconds to wet the surface of the aggregate; Step 2: Pour in 760.6g of water-based epoxy resin emulsified asphalt and stir for 60 seconds; Step 3: Add 169.5g of cement, 16.95g of fiber and 339g of mineral powder and mix for 60 seconds to obtain the cold patching material.

[0040] Step 4: Concrete the mold on both sides 50 times at room temperature, then cure it in a 60℃ oven for 3 hours. Step 5: After compacting 25 times again, demold and continue curing for 48 hours.

[0041] Tests and trials Experiment 1 To verify the comprehensive performance of the cold patch material of this application, in accordance with the relevant provisions of T0738-2025 "Dynamic Modulus Test of Asphalt Mixture (Uniaxial Compression Method)" in JTG 3410-2025 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the dynamic modulus of the "Waterborne Epoxy-Cement-Fiber Reinforced Cold Patch Material for Emergency Repair of Asphalt Pavement in Low Temperature and Foggy Mountain Areas" was tested using a UTM-30 universal testing machine.

[0042] Five typical temperature gradients (-10℃, 5℃, 20℃, 35℃, and 50℃) were selected for the test, covering low-temperature icing in mountainous areas, normal temperature, and high-temperature service conditions. The loading frequencies were set to 0.1Hz, 0.5Hz, 1Hz, 5Hz, 10Hz, and 25Hz to simulate the load characteristics corresponding to different vehicle speeds. Through standard specimen preparation and testing procedures, the dynamic modulus data of the material under different temperature and frequency conditions were obtained systematically. The test results are shown in Table 3.

[0043] Table 3. Test results of dynamic modulus of waterborne epoxy-cement-fiber reinforced cold patching material

[0044] The dynamic modulus test results of the cold-applied patching material in this application show that the material exhibits excellent mechanical properties and service stability under low-temperature conditions, effectively adapting to the harsh environment of mountainous areas with frequent low-temperature icing and fog. Under the test conditions of -10℃, the dynamic modulus of the material remains at a high level at different loading frequencies, reaching 16793MPa at a low frequency of 0.1Hz and as high as 32346MPa at a high frequency of 25Hz. The overall stiffness is sufficient, effectively resisting permanent deformation and load in the low-temperature environment of winter, avoiding early loosening, settlement and other defects caused by insufficient low-temperature strength. At the same time, within the low-temperature range of -10℃, the modulus shows a continuous and stable growth trend with the frequency from 0.1Hz to 25Hz, without abrupt changes or abnormal fluctuations. This indicates that the material has good adaptability to the load frequencies corresponding to different driving speeds at low temperatures, with stable mechanical response, which can effectively reduce the risk of stress concentration and local damage.

[0045] From the perspective of temperature sensitivity, the modulus change of the material in the low-temperature range (-10℃~5℃) is significantly smaller than that in the high-temperature range (35℃~50℃), and the stiffness stability in the low-temperature range is outstanding. This characteristic indicates that the material has good stress relaxation ability in low-temperature environments, which can effectively alleviate temperature stress under conditions of large diurnal temperature differences and low-temperature humid fog and icing in the mountainous areas of northern Fujian, inhibit the initiation and propagation of thermal shrinkage cracks, and exhibit excellent low-temperature crack resistance.

[0046] In addition, the material also exhibits good mechanical properties in the room temperature and medium-high temperature range. At 20℃, the modulus increases from 4138MPa to 15913MPa with increasing frequency. The modulus levels at 35℃ and 50℃ can also meet the load-bearing requirements at different temperatures. This indicates that the cold patch material is not only suitable for low-temperature emergency maintenance in mountainous areas, but also maintains stable road performance under different temperature conditions throughout the year, and has broad engineering application prospects.

[0047] Experiment 2 To simulate the damp and foggy conditions in mountainous areas, the aggregate was placed in a constant temperature and humidity chamber at 95% relative humidity and 10℃ for 24 hours to allow a water film to condense on its surface. Another batch of aggregate from the same batch was placed at 25℃ and relative humidity ≤60% for 24 hours as a drying reference material. Both groups of samples were prepared with cold-mixed materials according to the proportions in Example 1 and compacted under their respective environmental conditions. The splitting tensile strength of the specimens at 15℃ was determined according to JTG E20 T0716. Using the strength of the samples prepared from the dried aggregate as a benchmark, the strength retention rate of the samples under damp and foggy conditions was calculated. Detailed test data are shown in Table 4.

[0048] Table 4. Comparison of splitting tensile strength at 15℃ between dry aggregates and cold-mixed aggregates prepared under foggy conditions.

[0049] As shown in Table 4, the splitting strength of the humid aggregate specimen was 86.7% of that of the dry aggregate specimen, indicating that the cold patch material of the present invention can still maintain high mechanical properties in the humid fog environment of mountainous areas with high humidity and excellent construction tolerance and strength retention performance in low temperature and high humidity environments.

[0050] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a water-based epoxy-cement-fiber reinforced cold patching material for emergency repair of asphalt pavements in low-temperature, foggy mountainous areas, characterized in that, Includes the following steps: (1) Preparation of emulsifier: Prepare 200g of a mixed solution of epoxy resin E44 and polyethylene glycol PEG in a mass ratio of 1:1, place it in a constant temperature water bath at 60℃, adjust the speed of the mechanical stirrer to 300r / min, slowly add 10g of potassium persulfate solution with a mass fraction of 5%, and after titration for 30min, transfer it to an oil bath at 160℃ and react for 6h. (2) Preparation of waterborne epoxy resin emulsion: Emulsifier and epoxy resin E44 were added to a three-necked flask, the water bath heating temperature was controlled at 60℃, and the mixture was stirred at a mechanical speed of 2000r / min for 0.5h. Deionized water was added to prepare a waterborne epoxy resin emulsion with a solid content of 50wt%. (3) Preparation of waterborne epoxy resin emulsified asphalt: The waterborne curing agent modified polyamide is mixed with emulsified asphalt and mechanically stirred to obtain a mixture; then waterborne epoxy resin emulsion is added and mechanically stirred at 400 r / min for 3~4 min to obtain waterborne epoxy resin emulsified asphalt. (4) Select mineral powder with a relative density of 2.790, and add it at a rate of 2% to 6% of the total mass of the cold-mixed material; (5) Based on the total mass of the cold patching material, the fiber used is chopped polyester fiber with a fiber content of 0.2%; the cement is ordinary silicate P.I42.5 with a cement content of 2%; (6) Molding and mixing: Step 1: Put the aggregate and externally added water into the mixing pot and stir for 60 seconds to wet the surface of the aggregate; Step 2: Pour in the appropriate proportion of water-based epoxy resin emulsified asphalt and stir for 60 seconds; Step 3: Add the weighed cement, fiber and mineral powder and mix for 60 seconds to obtain the cold patching material.

2. The preparation method according to claim 1, characterized in that, In step (2), the amount of emulsifier used is 10%-30% of the mass of E44.

3. The preparation method according to claim 1, characterized in that, In step (6), the amount of waterborne epoxy resin emulsified asphalt binder is 8.975% of the total mass of the cold patch material.

4. The preparation method according to claim 1, characterized in that, In step (6), the amount of water added is 1.0% of the aggregate mass.

Images